The new ECMWF VAREPS (Variable Resolution Ensemble Prediction System)

Buizza, Roberto; Bidlot, Jean‐Raymond; Wedi, Nils; Fuentes, M.; Hamrud, Mats; Holt, Graham; Vitart, Frédéric

doi:10.1002/qj.75

Cited by 161 publications

(114 citation statements)

References 27 publications

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“…The ECMWF-EPS forecasts consist of 50 members of perturbed precipitation of 0.5 degrees resolution for the whole globe considering initial uncertainties by using singular vectors and model uncertainties due to physical parameterizations by a stochastic scheme (Buizza et al 2007). The data becomes available twice a day at 00:00 UTM and 12:00 UTM with a forecast horizon of 15 days and time steps of 6 hours.…”

Section: Ensemble Forecast Datamentioning

confidence: 99%

Short-Term Reservoir Optimization for Flood Mitigation under Meteorological and Hydrological Forecast Uncertainty

Schwanenberg

Fan

Naumann

et al. 2015

Water Resour Manage

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State-of-the-art applications of short-term reservoir management integrate several advanced components, namely hydrological modelling and data assimilation techniques for predicting streamflow, optimization-based techniques for decision-making on the reservoir operation and the technical framework for integrating these components with data feeds from gauging networks, remote sensing data and meteorological weather predictions. In this paper, we present such a framework for the short-term management of reservoirs operated by the a drainage area of approximately 55,000 km and its operation for flood mitigation. Basis for the anticipatory short-term management of the reservoir over a forecast horizon of up to 15 days are streamflow predictions of the MGB hydrological model. The semi-distributed model is well suited to represent the watershed and shows a Nash-Sutcliffe model performance in the order of 0.83-0.90 for most streamflow gauges of the data-sparse basin. A lead time performance assessment of the deterministic and probabilistic ECMWF forecasts as model forcing indicate the superiority of the probabilistic model. The novel short-term optimization approach consists of the reduction of the ensemble forecasts into scenario trees as an input of a multi-stage stochastic optimization. We show that this approach has several advantages over commonly used deterministic methods which neglect forecast uncertainty in the short-term decision-making. First, the probabilistic forecasts have longer forecast horizons that allow an earlier and therefore better anticipation of critical flood events. Second, the stochastic optimization leads to more robust decisions than deterministic procedures which consider only a single future trajectory. Third, the stochastic optimization permits to introduce advanced chance constraints for refining the system operation.

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Section: Ensemble Forecast Datamentioning

confidence: 99%

Short-Term Reservoir Optimization for Flood Mitigation under Meteorological and Hydrological Forecast Uncertainty

Schwanenberg

Fan

Naumann

et al. 2015

Water Resour Manage

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“…Interest from the international community has also resulted in the system being implemented at ECMWF to run on the VAREPS (Variable Resolution Ensemble Prediction System, described in Buizza et al (2007)). …”

Section: Applicationsmentioning

confidence: 99%

Objective identification, typing and tracking of the complete life-cycles of cyclonic features at high spatial resolution

Hewson

Titley

2010

Met. Apps

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Synoptic-scale cyclonic features provide an inescapable focal point for operational forecasting, whilst the merits of tracking such features are increasingly being recognized in the climate change field. Close association with adverse and extreme weather is the main motivator. Here a new and highly sophisticated set of techniques to detect, classify and track the full range is developed. A revised conceptual model of cyclone development provided the initial framework, ensuring a solid bond with forecasting practice, whilst also connecting closely to baroclinic life-cycle concepts. Building on this, cyclones are detected using a hybrid of geopotential minimum/vorticity maximum techniques, whilst incorporating important extensions to ensure that vorticity can be used at high resolution (∼50 km) and that features on fronts take priority. To track the features across time, at intervals of 12 h or less, feature attributes in the association process are used. Additionally, an upper-tropospheric steering wind is employed to estimate future and past positions. This facilitates 'half-time tracking', a new approach that has clear-cut advantages over 'full-time tracking' employed elsewhere.In detection tests, comparing with subjectively-drawn charts, the feature hit rate was 84%, and the false alarm ratio 17%, whilst in a simple tracking test the association failure rate was just 2%. These values compare very favourably with previous studies.One key application is discussed. This involves processing ensemble output to provide wide-ranging real-time products tailor-made to forecasters' needs. Products include track-following plume diagrams, for various cyclone attributes, and storm-track strike probability plots for different thresholds of severity.

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“…For the probabilistic flood forecast, the European Centre for Medium-Range Weather Forecasts (ECMWF)-VAREPS data (Table II; Buizza et al, 2007;Vitart et al, 2008) were used, which were specifically recalculated for this case study by ECMWF, using the latest model version (cycle 33R3, Buizza, 2009).…”

Section: Description Of the Study Area Input Data Model Set-up And mentioning

confidence: 99%

Ensemble flood forecasting in Africa: a feasibility study in the Juba–Shabelle river basin

Thiemig

Pappenberger

Thielen

et al. 2010

Atmospheric Science Letters

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The European flood alert system (EFAS) achieves early flood warnings for large to mediumsize river basins with lead times of 10 days. This is based on probabilistic weather forecasts, the exceedance of alert thresholds and persistence. The methodologies have been tested for different events and time scales in mid-latitude basins in Europe. In this article, the transferability of the EFAS-methodologies to equatorial African basins is assessed with the analysis of the Juba-Shabelle river basin as an example using a variety of different meteorological data sources. In this context, ERA-40 and CHARM have been used for the calculation of climatologies; re-forecasts of the current operational European Centre for Medium-Range Weather Forecasts model provided hindcasts of historic flood events. The results show that flood events have been detected successfully in more than 85% of all cases, with a high accuracy in terms of timing and magnitude.

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The new ECMWF VAREPS (Variable Resolution Ensemble Prediction System)

Cited by 161 publications

References 27 publications

Short-Term Reservoir Optimization for Flood Mitigation under Meteorological and Hydrological Forecast Uncertainty

Short-Term Reservoir Optimization for Flood Mitigation under Meteorological and Hydrological Forecast Uncertainty

Objective identification, typing and tracking of the complete life-cycles of cyclonic features at high spatial resolution

Ensemble flood forecasting in Africa: a feasibility study in the Juba–Shabelle river basin

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